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Date:: Fri Jan 26 14:01:44 2018 UTC
Message:: ensure we don't call closedir(NULL) in search_packidx()
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1 /*
2  * Copyright (c) 2018 Stefan Sperling <stsp@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <sys/types.h>
18 #include <sys/stat.h>
19 #include <sys/queue.h>
20 
21 #include <dirent.h>
22 #include <errno.h>
23 #include <stdio.h>
24 #include <stdint.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <limits.h>
28 #include <sha1.h>
29 #include <endian.h>
30 #include <zlib.h>
31 
32 #include "got_error.h"
33 #include "got_object.h"
34 #include "got_repository.h"
35 #include "got_sha1.h"
36 #include "pack.h"
37 #include "path.h"
38 #include "delta.h"
39 #include "object.h"
40 
41 #define GOT_PACK_PREFIX		"pack-"
42 #define GOT_PACKFILE_SUFFIX	".pack"
43 #define GOT_PACKIDX_SUFFIX		".idx"
44 #define GOT_PACKFILE_NAMELEN	(strlen(GOT_PACK_PREFIX) + \
45 				SHA1_DIGEST_STRING_LENGTH - 1 + \
46 				strlen(GOT_PACKFILE_SUFFIX))
47 #define GOT_PACKIDX_NAMELEN	(strlen(GOT_PACK_PREFIX) + \
48 				SHA1_DIGEST_STRING_LENGTH - 1 + \
49 				strlen(GOT_PACKIDX_SUFFIX))
50 
51 #ifndef MIN
52 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
53 #endif
54 
55 static const struct got_error *
56 verify_fanout_table(uint32_t *fanout_table)
57 {
58 	int i;
59 
60 	for (i = 0; i < 0xff - 1; i++) {
61 		if (be32toh(fanout_table[i]) > be32toh(fanout_table[i + 1]))
62 			return got_error(GOT_ERR_BAD_PACKIDX);
63 	}
64 
65 	return NULL;
66 }
67 
68 static const struct got_error *
69 get_packfile_size(size_t *size, const char *path_idx)
70 {
71 	struct stat sb;
72 	char *path_pack;
73 	char base_path[PATH_MAX];
74 	char *dot;
75 
76 	if (strlcpy(base_path, path_idx, PATH_MAX) > PATH_MAX)
77 		return got_error(GOT_ERR_NO_SPACE);
78 
79 	dot = strrchr(base_path, '.');
80 	if (dot == NULL)
81 		return got_error(GOT_ERR_BAD_PATH);
82 	*dot = '\0';
83 	if (asprintf(&path_pack, "%s.pack", base_path) == -1)
84 		return got_error(GOT_ERR_NO_MEM);
85 
86 	if (stat(path_pack, &sb) != 0) {
87 		free(path_pack);
88 		return got_error_from_errno();
89 	}
90 
91 	free(path_pack);
92 	*size = sb.st_size;
93 	return 0;
94 }
95 
96 const struct got_error *
97 got_packidx_open(struct got_packidx_v2_hdr **packidx, const char *path)
98 {
99 	struct got_packidx_v2_hdr *p;
100 	FILE *f;
101 	const struct got_error *err = NULL;
102 	size_t n, nobj, packfile_size;
103 	SHA1_CTX ctx;
104 	uint8_t sha1[SHA1_DIGEST_LENGTH];
105 
106 	SHA1Init(&ctx);
107 
108 	f = fopen(path, "rb");
109 	if (f == NULL)
110 		return got_error(GOT_ERR_BAD_PATH);
111 
112 	err = get_packfile_size(&packfile_size, path);
113 	if (err)
114 		return err;
115 
116 	p = calloc(1, sizeof(*p));
117 	if (p == NULL) {
118 		err = got_error(GOT_ERR_NO_MEM);
119 		goto done;
120 	}
121 
122 	n = fread(&p->magic, sizeof(p->magic), 1, f);
123 	if (n != 1) {
124 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
125 		goto done;
126 	}
127 
128 	if (betoh32(p->magic) != GOT_PACKIDX_V2_MAGIC) {
129 		err = got_error(GOT_ERR_BAD_PACKIDX);
130 		goto done;
131 	}
132 
133 	SHA1Update(&ctx, (uint8_t *)&p->magic, sizeof(p->magic));
134 
135 	n = fread(&p->version, sizeof(p->version), 1, f);
136 	if (n != 1) {
137 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
138 		goto done;
139 	}
140 
141 	if (betoh32(p->version) != GOT_PACKIDX_VERSION) {
142 		err = got_error(GOT_ERR_BAD_PACKIDX);
143 		goto done;
144 	}
145 
146 	SHA1Update(&ctx, (uint8_t *)&p->version, sizeof(p->version));
147 
148 	n = fread(&p->fanout_table, sizeof(p->fanout_table), 1, f);
149 	if (n != 1) {
150 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
151 		goto done;
152 	}
153 
154 	err = verify_fanout_table(p->fanout_table);
155 	if (err)
156 		goto done;
157 
158 	SHA1Update(&ctx, (uint8_t *)p->fanout_table, sizeof(p->fanout_table));
159 
160 	nobj = betoh32(p->fanout_table[0xff]);
161 
162 	p->sorted_ids = calloc(nobj, sizeof(*p->sorted_ids));
163 	if (p->sorted_ids == NULL) {
164 		err = got_error(GOT_ERR_NO_MEM);
165 		goto done;
166 	}
167 
168 	n = fread(p->sorted_ids, sizeof(*p->sorted_ids), nobj, f);
169 	if (n != nobj) {
170 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
171 		goto done;
172 	}
173 
174 	SHA1Update(&ctx, (uint8_t *)p->sorted_ids,
175 	    nobj * sizeof(*p->sorted_ids));
176 
177 	p->crc32 = calloc(nobj, sizeof(*p->crc32));
178 	if (p->crc32 == NULL) {
179 		err = got_error(GOT_ERR_NO_MEM);
180 		goto done;
181 	}
182 
183 	n = fread(p->crc32, sizeof(*p->crc32), nobj, f);
184 	if (n != nobj) {
185 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
186 		goto done;
187 	}
188 
189 	SHA1Update(&ctx, (uint8_t *)p->crc32, nobj * sizeof(*p->crc32));
190 
191 	p->offsets = calloc(nobj, sizeof(*p->offsets));
192 	if (p->offsets == NULL) {
193 		err = got_error(GOT_ERR_NO_MEM);
194 		goto done;
195 	}
196 
197 	n = fread(p->offsets, sizeof(*p->offsets), nobj, f);
198 	if (n != nobj) {
199 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
200 		goto done;
201 	}
202 
203 	SHA1Update(&ctx, (uint8_t *)p->offsets, nobj * sizeof(*p->offsets));
204 
205 	/* Large file offsets are contained only in files > 2GB. */
206 	if (packfile_size <= 0x80000000)
207 		goto checksum;
208 
209 	p->large_offsets = calloc(nobj, sizeof(*p->large_offsets));
210 	if (p->large_offsets == NULL) {
211 		err = got_error(GOT_ERR_NO_MEM);
212 		goto done;
213 	}
214 
215 	n = fread(p->large_offsets, sizeof(*p->large_offsets), nobj, f);
216 	if (n != nobj) {
217 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
218 		goto done;
219 	}
220 
221 	SHA1Update(&ctx, (uint8_t*)p->large_offsets,
222 	    nobj * sizeof(*p->large_offsets));
223 
224 checksum:
225 	n = fread(&p->trailer, sizeof(p->trailer), 1, f);
226 	if (n != 1) {
227 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
228 		goto done;
229 	}
230 
231 	SHA1Update(&ctx, p->trailer.packfile_sha1, SHA1_DIGEST_LENGTH);
232 	SHA1Final(sha1, &ctx);
233 	if (memcmp(p->trailer.packidx_sha1, sha1, SHA1_DIGEST_LENGTH) != 0)
234 		err = got_error(GOT_ERR_PACKIDX_CSUM);
235 done:
236 	fclose(f);
237 	if (err)
238 		got_packidx_close(p);
239 	else
240 		*packidx = p;
241 	return err;
242 }
243 
244 void
245 got_packidx_close(struct got_packidx_v2_hdr *packidx)
246 {
247 	free(packidx->sorted_ids);
248 	free(packidx->offsets);
249 	free(packidx->crc32);
250 	free(packidx->large_offsets);
251 	free(packidx);
252 }
253 
254 static int
255 is_packidx_filename(const char *name, size_t len)
256 {
257 	if (len != GOT_PACKIDX_NAMELEN)
258 		return 0;
259 
260 	if (strncmp(name, GOT_PACK_PREFIX, strlen(GOT_PACK_PREFIX)) != 0)
261 		return 0;
262 
263 	if (strcmp(name + strlen(GOT_PACK_PREFIX) +
264 	    SHA1_DIGEST_STRING_LENGTH - 1, GOT_PACKIDX_SUFFIX) != 0)
265 		return 0;
266 
267 	return 1;
268 }
269 
270 static off_t
271 get_object_offset(struct got_packidx_v2_hdr *packidx, int idx)
272 {
273 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
274 	uint32_t offset = betoh32(packidx->offsets[idx]);
275 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
276 		uint64_t loffset;
277 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
278 		if (idx < 0 || idx > totobj || packidx->large_offsets == NULL)
279 			return -1;
280 		loffset = betoh64(packidx->large_offsets[idx]);
281 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
282 	}
283 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
284 }
285 
286 static int
287 get_object_idx(struct got_packidx_v2_hdr *packidx, struct got_object_id *id)
288 {
289 	u_int8_t id0 = id->sha1[0];
290 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
291 	int i = 0;
292 
293 	if (id0 > 0)
294 		i = betoh32(packidx->fanout_table[id0 - 1]);
295 
296 	while (i < totobj) {
297 		struct got_object_id *oid = &packidx->sorted_ids[i];
298 		uint32_t offset;
299 		int cmp = got_object_id_cmp(id, oid);
300 
301 		if (cmp == 0)
302 			return i;
303 		else if (cmp > 0)
304 			break;
305 		i++;
306 	}
307 
308 	return -1;
309 }
310 
311 static const struct got_error *
312 search_packidx(struct got_packidx_v2_hdr **packidx, int *idx,
313     struct got_repository *repo, struct got_object_id *id)
314 {
315 	const struct got_error *err;
316 	char *path_packdir;
317 	DIR *packdir;
318 	struct dirent *dent;
319 	char *path_packidx;
320 
321 	path_packdir = got_repo_get_path_objects_pack(repo);
322 	if (path_packdir == NULL)
323 		return got_error(GOT_ERR_NO_MEM);
324 
325 	packdir = opendir(path_packdir);
326 	if (packdir == NULL) {
327 		err = got_error_from_errno();
328 		goto done;
329 	}
330 
331 	while ((dent = readdir(packdir)) != NULL) {
332 		if (!is_packidx_filename(dent->d_name, dent->d_namlen))
333 			continue;
334 
335 		if (asprintf(&path_packidx, "%s/%s", path_packdir,
336 		    dent->d_name) == -1) {
337 			err = got_error(GOT_ERR_NO_MEM);
338 			goto done;
339 		}
340 
341 		err = got_packidx_open(packidx, path_packidx);
342 		free(path_packidx);
343 		if (err)
344 			goto done;
345 
346 		*idx = get_object_idx(*packidx, id);
347 		if (*idx != -1) {
348 			err = NULL; /* found the object */
349 			goto done;
350 		}
351 
352 		got_packidx_close(*packidx);
353 		*packidx = NULL;
354 	}
355 
356 	err = got_error(GOT_ERR_NO_OBJ);
357 done:
358 	free(path_packdir);
359 	if (packdir && closedir(packdir) != 0 && err == 0)
360 		err = got_error_from_errno();
361 	return err;
362 }
363 
364 static const struct got_error *
365 get_packfile_path(char **path_packfile, struct got_repository *repo,
366     struct got_packidx_v2_hdr *packidx)
367 {
368 	char *path_packdir;
369 	char hex[SHA1_DIGEST_STRING_LENGTH];
370 	char *sha1str;
371 	char *path_packidx;
372 
373 	*path_packfile = NULL;
374 
375 	path_packdir = got_repo_get_path_objects_pack(repo);
376 	if (path_packdir == NULL)
377 		return got_error(GOT_ERR_NO_MEM);
378 
379 	sha1str = got_sha1_digest_to_str(packidx->trailer.packfile_sha1,
380 	    hex, sizeof(hex));
381 	if (sha1str == NULL)
382 		return got_error(GOT_ERR_PACKIDX_CSUM);
383 
384 	if (asprintf(path_packfile, "%s/%s%s%s", path_packdir,
385 	    GOT_PACK_PREFIX, sha1str, GOT_PACKFILE_SUFFIX) == -1) {
386 		*path_packfile = NULL;
387 		return got_error(GOT_ERR_NO_MEM);
388 	}
389 
390 	return NULL;
391 }
392 
393 const struct got_error *
394 read_packfile_hdr(FILE *f, struct got_packidx_v2_hdr *packidx)
395 {
396 	const struct got_error *err = NULL;
397 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
398 	struct got_packfile_hdr hdr;
399 	size_t n;
400 
401 	n = fread(&hdr, sizeof(hdr), 1, f);
402 	if (n != 1)
403 		return got_ferror(f, GOT_ERR_BAD_PACKIDX);
404 
405 	if (betoh32(hdr.signature) != GOT_PACKFILE_SIGNATURE ||
406 	    betoh32(hdr.version) != GOT_PACKFILE_VERSION ||
407 	    betoh32(hdr.nobjects) != totobj)
408 		err = got_error(GOT_ERR_BAD_PACKFILE);
409 
410 	return err;
411 }
412 
413 static const struct got_error *
414 open_packfile(FILE **packfile, char **path_packfile,
415     struct got_repository *repo, struct got_packidx_v2_hdr *packidx)
416 {
417 	const struct got_error *err;
418 
419 	*packfile = NULL;
420 
421 	err = get_packfile_path(path_packfile, repo, packidx);
422 	if (err)
423 		return err;
424 
425 	*packfile = fopen(*path_packfile, "rb");
426 	if (*packfile == NULL) {
427 		err = got_error_from_errno();
428 		free(*path_packfile);
429 		return err;
430 	}
431 
432 	err = read_packfile_hdr(*packfile, packidx);
433 	if (err) {
434 		fclose(*packfile);
435 		*packfile = NULL;
436 	}
437 	return err;
438 }
439 
440 static const struct got_error *
441 parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
442     FILE *packfile)
443 {
444 	uint8_t t = 0;
445 	uint64_t s = 0;
446 	uint8_t sizeN;
447 	size_t n;
448 	int i = 0;
449 
450 	do {
451 		/* We do not support size values which don't fit in 64 bit. */
452 		if (i > 9)
453 			return got_error(GOT_ERR_NO_SPACE);
454 
455 		n = fread(&sizeN, sizeof(sizeN), 1, packfile);
456 		if (n != 1)
457 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
458 
459 		if (i == 0) {
460 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
461 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
462 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
463 		} else {
464 			size_t shift = 4 + 7 * (i - 1);
465 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
466 		}
467 		i++;
468 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
469 
470 	*type = t;
471 	*size = s;
472 	*len = i * sizeof(sizeN);
473 	return NULL;
474 }
475 
476 static const struct got_error *
477 open_plain_object(struct got_object **obj, const char *path_packfile,
478     struct got_object_id *id, uint8_t type, off_t offset, size_t size)
479 {
480 	*obj = calloc(1, sizeof(**obj));
481 	if (*obj == NULL)
482 		return got_error(GOT_ERR_NO_MEM);
483 
484 	(*obj)->path_packfile = strdup(path_packfile);
485 	if ((*obj)->path_packfile == NULL) {
486 		free(*obj);
487 		*obj = NULL;
488 		return got_error(GOT_ERR_NO_MEM);
489 	}
490 
491 	(*obj)->type = type;
492 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
493 	(*obj)->hdrlen = 0;
494 	(*obj)->size = size;
495 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
496 	(*obj)->pack_offset = offset;
497 
498 	return NULL;
499 }
500 
501 static const struct got_error *
502 parse_negative_offset(int64_t *offset, size_t *len, FILE *packfile)
503 {
504 	int64_t o = 0;
505 	uint8_t offN;
506 	size_t n;
507 	int i = 0;
508 
509 	do {
510 		/* We do not support offset values which don't fit in 64 bit. */
511 		if (i > 8)
512 			return got_error(GOT_ERR_NO_SPACE);
513 
514 		n = fread(&offN, sizeof(offN), 1, packfile);
515 		if (n != 1)
516 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
517 
518 		if (i == 0)
519 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
520 		else {
521 			o++;
522 			o <<= 7;
523 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
524 		}
525 		i++;
526 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
527 
528 	*offset = o;
529 	*len = i * sizeof(offN);
530 	return NULL;
531 }
532 
533 static const struct got_error *
534 parse_offset_delta(off_t *base_offset, FILE *packfile, off_t offset)
535 {
536 	const struct got_error *err;
537 	int64_t negoffset;
538 	size_t negofflen;
539 
540 	err = parse_negative_offset(&negoffset, &negofflen, packfile);
541 	if (err)
542 		return err;
543 
544 	/* Compute the base object's offset (must be in the same pack file). */
545 	*base_offset = (offset - negoffset);
546 	if (*base_offset <= 0)
547 		return got_error(GOT_ERR_BAD_PACKFILE);
548 
549 	return NULL;
550 }
551 
552 static const struct got_error *resolve_delta_chain(struct got_delta_chain *,
553     struct got_repository *repo, FILE *, const char *, int, off_t, size_t);
554 
555 static const struct got_error *
556 resolve_offset_delta(struct got_delta_chain *deltas,
557     struct got_repository *repo, FILE *packfile, const char *path_packfile,
558     off_t delta_offset)
559 {
560 	const struct got_error *err;
561 	off_t base_offset;
562 	uint8_t base_type;
563 	uint64_t base_size;
564 	size_t base_tslen;
565 
566 	err = parse_offset_delta(&base_offset, packfile, delta_offset);
567 	if (err)
568 		return err;
569 
570 	/* An offset delta must be in the same packfile. */
571 	if (fseeko(packfile, base_offset, SEEK_SET) != 0)
572 		return got_error_from_errno();
573 
574 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
575 	    packfile);
576 	if (err)
577 		return err;
578 
579 	return resolve_delta_chain(deltas, repo, packfile, path_packfile,
580 	    base_type, base_offset + base_tslen, base_size);
581 }
582 
583 static const struct got_error *
584 resolve_ref_delta(struct got_delta_chain *deltas, struct got_repository *repo,
585     FILE *packfile, const char *path_packfile, off_t delta_offset)
586 {
587 	const struct got_error *err;
588 	struct got_object_id id;
589 	struct got_packidx_v2_hdr *packidx;
590 	int idx;
591 	off_t base_offset;
592 	uint8_t base_type;
593 	uint64_t base_size;
594 	size_t base_tslen;
595 	size_t n;
596 	FILE *base_packfile;
597 	char *path_base_packfile;
598 
599 	n = fread(&id, sizeof(id), 1, packfile);
600 	if (n != 1)
601 		return got_ferror(packfile, GOT_ERR_IO);
602 
603 	err = search_packidx(&packidx, &idx, repo, &id);
604 	if (err)
605 		return err;
606 
607 	base_offset = get_object_offset(packidx, idx);
608 	if (base_offset == (uint64_t)-1) {
609 		got_packidx_close(packidx);
610 		return got_error(GOT_ERR_BAD_PACKIDX);
611 	}
612 
613 	err = open_packfile(&base_packfile, &path_base_packfile, repo, packidx);
614 	got_packidx_close(packidx);
615 	if (err)
616 		return err;
617 
618 	if (fseeko(base_packfile, base_offset, SEEK_SET) != 0) {
619 		err = got_error_from_errno();
620 		goto done;
621 	}
622 
623 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
624 	    base_packfile);
625 	if (err)
626 		goto done;
627 
628 	err = resolve_delta_chain(deltas, repo, base_packfile,
629 	    path_base_packfile, base_type, base_offset + base_tslen, base_size);
630 done:
631 	free(path_base_packfile);
632 	if (base_packfile && fclose(base_packfile) == -1 && err == 0)
633 		err = got_error_from_errno();
634 	return err;
635 }
636 
637 static const struct got_error *
638 resolve_delta_chain(struct got_delta_chain *deltas, struct got_repository *repo,
639     FILE *packfile, const char *path_packfile, int delta_type,
640     off_t delta_offset, size_t delta_size)
641 {
642 	const struct got_error *err = NULL;
643 	struct got_delta *delta;
644 
645 	delta = got_delta_open(path_packfile, delta_type, delta_offset,
646 	    delta_size);
647 	if (delta == NULL)
648 		return got_error(GOT_ERR_NO_MEM);
649 	deltas->nentries++;
650 	SIMPLEQ_INSERT_HEAD(&deltas->entries, delta, entry);
651 	/* In case of error below, delta is freed in got_object_close(). */
652 
653 	switch (delta_type) {
654 	case GOT_OBJ_TYPE_COMMIT:
655 	case GOT_OBJ_TYPE_TREE:
656 	case GOT_OBJ_TYPE_BLOB:
657 	case GOT_OBJ_TYPE_TAG:
658 		/* Plain types are the final delta base. Recursion ends. */
659 		break;
660 	case GOT_OBJ_TYPE_OFFSET_DELTA:
661 		err = resolve_offset_delta(deltas, repo, packfile,
662 		    path_packfile, delta_offset);
663 		break;
664 	case GOT_OBJ_TYPE_REF_DELTA:
665 		err = resolve_ref_delta(deltas, repo, packfile, path_packfile,
666 		    delta_offset);
667 		break;
668 	default:
669 		return got_error(GOT_ERR_NOT_IMPL);
670 	}
671 
672 	return err;
673 }
674 
675 static const struct got_error *
676 open_delta_object(struct got_object **obj, struct got_repository *repo,
677     struct got_packidx_v2_hdr *packidx, const char *path_packfile,
678     FILE *packfile, struct got_object_id *id, off_t offset, size_t tslen,
679     int delta_type, size_t delta_size)
680 {
681 	const struct got_error *err = NULL;
682 	struct got_object_id base_id;
683 	uint8_t base_type;
684 	int resolved_type;
685 	uint64_t base_size;
686 	size_t base_tslen;
687 
688 	*obj = calloc(1, sizeof(**obj));
689 	if (*obj == NULL)
690 		return got_error(GOT_ERR_NO_MEM);
691 
692 	(*obj)->flags = 0;
693 	(*obj)->hdrlen = 0;
694 	(*obj)->size = 0; /* Not yet known because deltas aren't combined. */
695 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
696 	(*obj)->pack_offset = offset + tslen;
697 
698 	(*obj)->path_packfile = strdup(path_packfile);
699 	if ((*obj)->path_packfile == NULL) {
700 		err = got_error(GOT_ERR_NO_MEM);
701 		goto done;
702 	}
703 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
704 
705 	SIMPLEQ_INIT(&(*obj)->deltas.entries);
706 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
707 
708 	err = resolve_delta_chain(&(*obj)->deltas, repo, packfile,
709 	    path_packfile, delta_type, offset, delta_size);
710 	if (err)
711 		goto done;
712 
713 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
714 	if (err)
715 		goto done;
716 	(*obj)->type = resolved_type;
717 
718 done:
719 	if (err) {
720 		got_object_close(*obj);
721 		*obj = NULL;
722 	}
723 	return err;
724 }
725 
726 static const struct got_error *
727 open_packed_object(struct got_object **obj, struct got_repository *repo,
728     struct got_packidx_v2_hdr *packidx, int idx, struct got_object_id *id)
729 {
730 	const struct got_error *err = NULL;
731 	off_t offset;
732 	char *path_packfile;
733 	FILE *packfile;
734 	uint8_t type;
735 	uint64_t size;
736 	size_t tslen;
737 
738 	*obj = NULL;
739 
740 	offset = get_object_offset(packidx, idx);
741 	if (offset == (uint64_t)-1)
742 		return got_error(GOT_ERR_BAD_PACKIDX);
743 
744 	err = open_packfile(&packfile, &path_packfile, repo, packidx);
745 	if (err)
746 		return err;
747 
748 	if (fseeko(packfile, offset, SEEK_SET) != 0) {
749 		err = got_error_from_errno();
750 		goto done;
751 	}
752 
753 	err = parse_object_type_and_size(&type, &size, &tslen, packfile);
754 	if (err)
755 		goto done;
756 
757 	switch (type) {
758 	case GOT_OBJ_TYPE_COMMIT:
759 	case GOT_OBJ_TYPE_TREE:
760 	case GOT_OBJ_TYPE_BLOB:
761 	case GOT_OBJ_TYPE_TAG:
762 		err = open_plain_object(obj, path_packfile, id, type,
763 		    offset + tslen, size);
764 		break;
765 
766 	case GOT_OBJ_TYPE_OFFSET_DELTA:
767 	case GOT_OBJ_TYPE_REF_DELTA:
768 		err = open_delta_object(obj, repo, packidx, path_packfile,
769 		    packfile, id, offset, tslen, type, size);
770 		break;
771 
772 	default:
773 		err = got_error(GOT_ERR_NOT_IMPL);
774 		goto done;
775 	}
776 done:
777 	free(path_packfile);
778 	if (packfile && fclose(packfile) == -1 && err == 0)
779 		err = got_error_from_errno();
780 	return err;
781 }
782 
783 const struct got_error *
784 got_packfile_open_object(struct got_object **obj, struct got_object_id *id,
785     struct got_repository *repo)
786 {
787 	const struct got_error *err = NULL;
788 	struct got_packidx_v2_hdr *packidx = NULL;
789 	int idx;
790 
791 	err = search_packidx(&packidx, &idx, repo, id);
792 	if (err)
793 		return err;
794 
795 	err = open_packed_object(obj, repo, packidx, idx, id);
796 	got_packidx_close(packidx);
797 	return err;
798 }
799 
800 static const struct got_error *
801 dump_plain_object(FILE *infile, uint8_t type, size_t size, FILE *outfile)
802 {
803 	size_t n;
804 
805 	while (size > 0) {
806 		uint8_t data[2048];
807 		size_t len = MIN(size, sizeof(data));
808 
809 		n = fread(data, len, 1, infile);
810 		if (n != 1)
811 			return got_ferror(infile, GOT_ERR_BAD_PACKFILE);
812 
813 		n = fwrite(data, len, 1, outfile);
814 		if (n != 1)
815 			return got_ferror(outfile, GOT_ERR_IO);
816 
817 		size -= len;
818 	}
819 
820 	rewind(outfile);
821 	return NULL;
822 }
823 
824 static const struct got_error *
825 dump_delta_chain(struct got_delta_chain *deltas, FILE *outfile)
826 {
827 	const struct got_error *err = NULL;
828 	struct got_delta *delta;
829 	FILE *base_file, *accum_file;
830 	int n = 0;
831 
832 	if (SIMPLEQ_EMPTY(&deltas->entries))
833 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
834 
835 	base_file = got_opentemp();
836 	if (base_file == NULL)
837 		return got_error_from_errno();
838 
839 	accum_file = got_opentemp();
840 	if (accum_file == NULL) {
841 		err = got_error_from_errno();
842 		fclose(base_file);
843 		return err;
844 	}
845 
846 	/* Deltas are ordered in ascending order. */
847 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
848 		FILE *delta_file = fopen(delta->path_packfile, "rb");
849 		if (delta_file == NULL) {
850 			err = got_error_from_errno();
851 			goto done;
852 		}
853 
854 		if (fseeko(delta_file, delta->offset, SEEK_SET) != 0) {
855 			fclose(delta_file);
856 			err = got_error_from_errno();
857 			goto done;
858 		}
859 
860 		err = got_delta_apply(delta, base_file, delta_file,
861 		    /* Final delta application writes to the output file. */
862 		    ++n < deltas->nentries ? accum_file : outfile);
863 		fclose(delta_file);
864 		if (err)
865 			goto done;
866 
867 		if (n < deltas->nentries) {
868 			/* Accumulated delta becomes the new base. */
869 			FILE *tmp = accum_file;
870 			accum_file = base_file;
871 			base_file = tmp;
872 			rewind(base_file);
873 			rewind(accum_file);
874 		}
875 	}
876 
877 done:
878 	fclose(base_file);
879 	fclose(accum_file);
880 	rewind(outfile);
881 	return err;
882 }
883 
884 const struct got_error *
885 got_packfile_extract_object(FILE **f, struct got_object *obj,
886     struct got_repository *repo)
887 {
888 	const struct got_error *err = NULL;
889 	FILE *packfile = NULL;
890 
891 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
892 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
893 
894 	*f = got_opentemp();
895 	if (*f == NULL) {
896 		err = got_error(GOT_ERR_FILE_OPEN);
897 		goto done;
898 	}
899 
900 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
901 		packfile = fopen(obj->path_packfile, "rb");
902 		if (packfile == NULL) {
903 			err = got_error_from_errno();
904 			goto done;
905 		}
906 
907 		if (fseeko(packfile, obj->pack_offset, SEEK_SET) != 0) {
908 			err = got_error_from_errno();
909 			goto done;
910 		}
911 
912 		err = dump_plain_object(packfile, obj->type, obj->size, *f);
913 	} else
914 		err = dump_delta_chain(&obj->deltas, *f);
915 done:
916 	if (packfile)
917 		fclose(packfile);
918 	if (err && *f)
919 		fclose(*f);
920 	return err;
921 }